DE 197 13 813 C1 discloses a method in which a transfer of a partial portion from the intermediary storage which is configured as a fork is provided to a feed device which is configured as a conveyor belt. The feed device is moveable relative to the cutting device, in particular relative to its blade in vertical direction. Transferring a partial portion from the intermediary storage device to the conveying device is provided so that the intermediary storage device continuously moves away from the cutting device with the feed velocity and penetrates with its tongs into the intermediary spaces between adjacent drive belts of the conveying device. Thus the storage conditions, this means the vertical distance between the cutting plane and the top side of the slice that has been cut off last and already stored is being maintained constant. After transferring the partial portion to the conveying device it is required for keeping the storage conditions constant that the conveying device moves away with feed velocity from the cutting device while cutting off the slices that are still missing to form a complete portion. The feed device only stops this lowering process when the last slice of a portion has been cut off and deposited. Thereafter the horizontal extraction of the completed portion is initiated and the intermediary storage device that has been moved into its idle position in the mean time can be moved back into the cross section of the food strand in order to start receiving the next partial portion slice by slice.
It is disadvantageous for the known method that the intermediary storage device and also the feed device have to be synchronized in their vertical movements with the feed movement of the food strand in vertical direction. This places stringent requirements on the type of drives and on the control. In particular the point in time of the transfer when the partial portion switches from being placed on the intermediary storage to being placed on the feed device has to be determined precisely.
Another method is furthermore known from, for example, U.S. Pat. No. 3,842,692. The device as disclosed in this printed document in FIGS. 10 to 14 includes two intermediary storage devices which are transferrable from opposite directions from respective idle positions adjacent to the food strand cross section into their receiving positions below the food strand. The intermediary storage devices that are also moveably supported in feed direction in addition to a direction perpendicular to the feed direction are used in the known method to respectively receive a complete portion of the cut off slices in a form vertically stacked on top of one another in order to transfer them with a transfer element connected there between to a conveying device including a plurality of circumferential belts. The transfer element enters from the bottom side of the conveying device facing away from the food strand into intermediary spaces between adjacent belts and also penetrates intermediary spaces in the fork shaped intermediary storage device in order to approach the bottom side of the formed portion and in order to be able to receive them in a supporting manner.
The two intermediary storage devices are being used in order to be able to provide feeding of the food strand continuously, this means continuously without interruptions when transporting out completed portions. While one portion is still on the first intermediary storage device or is just being taken over by the transfer element, the second intermediary storage device is already in an idle position or in a receiving position moved under the cross section of the food strand, so that the cutting process can be continued without interruption.
This does not only provide advantages with respect to the cutting performance which is accordingly high based on the continuity of the cutting process, but also avoids interrupting the feed movement which is always critical. Deviations in the feed velocity, in particular a short term stoppage of the food strand leads to problems in the feed device due to vibrations namely in particular for softer and deformable foods (e.g. pork sausage, meat loaf, ham, sausage, cheese etc.). Due to calibrations nozzles shortly above the blade the feeding of the food strand has high friction. Additionally, there is a so called “slip stick effect” this means when undercutting a particular feeding force the food strand suddenly breaks loose, this means uneven feeding of the food strand occurs. Due to the strong dynamics of all movements longitudinal vibrations at the knife side end of the material strand cause the food strand to protrude by a small amount below the blade plane in spite of a wanted stop, which leads to cutting off small food pieces (snipping effect). In particular for self service packages using clear foil as packaging material slice fragments of this type are not acceptable since they are perceived as substantial optical deficiency. Providing a continuous feeding without interruption is therefore an essential prerequisite for obtaining high cutting performance and in particular first class cutting quality so that the cut off slices always have an identical geometry.
Whereas the latter problem has been solved for the method according to U.S. Pat. No. 3,842,698, its design complexity is high and the control algorithms for controlling the movements of the many device components are complex.